Over the last few decades, telecommunications carriers have been considering an inexpensive means of using optical fibers to support access to telecommunications services over a last mile of connection between residential and business customers and a central office of a telecommunications service provider. The greatest bandwidth requirement for telecommunications services for these customers is typically not greater than a couple of gigabits per second (Gbps). To support this bandwidth requirement, studies have shown that wavelength division multiplexed passive optical networks (WDM-PONs) are the access technology that has attracted the most interest and shown the greatest commercial potential.
Wavelength division multiplexed passive optical networks (WDM-PONs) provide high-speed broadband communication services using a unique wavelength assigned to each customer. Accordingly, wavelength division multiplexed passive optical networks (WDM-PONs) may protect the confidentiality of communications and easily accommodate various communication services and bandwidth capacities that may be required by customers. Also, additional customers may be easily added to wavelength division multiplexed passive optical networks (WDM-PONs) by adding a respective number of wavelengths.
In traditional wavelength division multiplexed passive optical networks (WDM-PONs), both an optical line terminal (OLT) and a plurality of optical network terminals (ONTs) may require an accurate biasing of a light source at a particular oscillation wavelength. A controlling circuit may be required to stabilize an output power of the light source. For example, the controlling circuit may adjust a bias current and/or a modulation current applied to the light source in order to maintain a desired output power detected by a monitoring photodiode (MPD).
Currently, the biasing of the light source may be monitored by detecting, via a monitoring photodiode (MPD), an average output power (PAVG) of the light source. However, several drawbacks are associated with detecting the average output power (PAVG) of the light sources. In particular, the average output power (PAVG) detected by the monitoring photodiode (MPD) may not be an accurate representation of an output power of the light source. As illustrated in FIG. 1, in the event that a low injection power is applied to the light source, the light source may be properly biased. However, in the event that a high injection power is applied to the light source, the high injection power may constitute a significant portion of the average output power (PAVG) detected by the monitoring photodiode (MPD). The monitoring photodiode (MPD) may detect a high average output power (PAVG) from the light source (e.g., because of the high injection power) and may erroneously instruct the controlling circuit to bias the light source below a threshold voltage and/or current (e.g., putting the light source in an OFF-state) and thus decrease the transmitted power. Also, by erroneously biasing the light source below a threshold voltage and/or current, an optical eye may be distorted due to a delay when turning the light source ON and OFF.
In view of the foregoing, it may be understood that there may be significant problems and shortcomings associated with current wavelength division multiplexed passive optical network (WDM-PON) technologies using seed injected Fabry Perot laser diode (FP-LD) and/or a reflective semiconductor optical amplifier (RSOA) transmitter source.